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Noob question. Dave explains away the drilled rotors but how about the slotted rotors, billed as slicing the pad down to give a new surface with each brake. Do these actually improve stopping performance or are they also just bling?

Adding to OP before mentioned mechanical (e.g fade) and external factors (e.g. friction) of stopping a car:Braking capability which depends on factors such as;

the type of braking system,

brake pad material,

brake alignment,

tire pressures,

tire tread and grip,

vehicle weight,

suspension system,

the co-efficient of friction of the road surface,

wind speed,

slope of road,

surface smoothness

the braking technique applied by the driver.

To truly discuss braking one must consider the following:

Human Perception Time

Human Reaction Time

Vehicle Reaction Time

Vehicle Braking Capability

The human perception time; is how long the driver takes to see the hazard, and the brain realize it is a hazard requiring an immediate reaction. This perception time can be as long as ¼ to ½ a second. Add to this human reaction time vary from ¼ - ¾ of a second. There two components of stopping distance are human factors and as such can be effected by tiredness, alcohol, fatigue and concentration levels. A perception and reaction time of 3 or 4 seconds is possible. A driver perhaps 1 second late in applying the brakes @ 60 mph the car would require about 100 feet further to stop.

Hmm something tells me you drive something bigger than a car for a living... I have heard all this before while getting my CDL.

And its all true, I just want to throw a tid bit more info into this whole mess.

Remember your not stopping HP just weight and momentum. Brake systems are designed on vehicles for their weight, sometimes stripping away that weight can cost you stopping distance if you no longer have enough friction, sometimes adding weight can also help you in stopping. All depends on how the brake system was designed for that vehicle.

I know stopping my Semi that weighs in closer to 80k is alot easier than stopping it when it ways in at 30k. Its how the brakes were designed, to hold that weight, when I have less weight I have less friction to the ground, takes me longer to stop.

New to the site, and impressed. This is totally solid and true, but if I hadn't experienced it I may not believe it.

Take it from me as an this is an extreme example, I bought a MY95 jdm impreza, fresh from Japan running approx 400whp, IT HAD STOCK CLAW CALIPERS, not even a one pot. Despite initial reservations they worked fine, only changing them as the car is to be used as a show & go car.

The OP oversimplified the problem. He neglected to explain that brakes have a fixed rate at which they can dissipate thermal energy. Adding more power to the engine gives you the ability to ask the braking system to dissipate the same thermal energy in a shorter time because you can ask them to stop a second (or 3rd, 4th, etc) time much sooner. Think about it this way, you can rip off 10 0-60-0mph speed runs in a much shorter time with 300hp than you can with 30hp. That drives your braking system up to a much higher temperature. Hell, you can feel this dramatically if you go out to bed new brakes in an RS vs WRX.

The OP is absolutely right, you don't upgrade the brakes when you make more power to stop in a shorter distance. You don't upgrade the brakes when you make more power to make sure you can still stop from 130mph when a deer runs into the road. The OP misses, however, that you upgrade the brakes when you make more power so that, after 30 minutes of yo-yoing between 20 and 70mph when you and your buddies go play in the hills, you stop at all.

Now, I also think the point that we should encourage people who add weight to their cars (stereos, whatever) to upgrade their brakes (again, for thermal reasons) is a damned good one.

I know stopping my Semi that weighs in closer to 80k is alot easier than stopping it when it ways in at 30k. Its how the brakes were designed, to hold that weight, when I have less weight I have less friction to the ground, takes me longer to stop.

this is mostly true for class A vehicles equipped with air brakes. I'm not sure this is as detrimental in hydraulic brakes as it is in air brakes. For hydraulic or mechanical, I was always under the impression that you get better braking by lightening up the vehicle whereas the opposite is true for air.

Stock WRX brakes, with HPS pads, and "ghetto" fluid WILL NOT NECCESSARILY hold up on a track day OR on spirited mountain twisties. I live on a mountain and my daily commute can evolve into spirited driving. On my first track day in my relatively recently acquired '07 WRX Wagon (converted to "STI" over the winter) (previous ride - SM/Track Day/DD MINI Cooper S). Track day resulted in nearly 0 pedal (near the end of a 15 minute run) after just a couple of 15 minute sessions, 45 minute cool down between sessions. Boiling fluid, overheated brakes = dangerous situation. Spirited street driving can also induce brake fade.

Manner of driving is a critical factor in considering what, if any, brake upgrades may be beneficial.

Can anyone recommend any good blank rotors besides oem/brembo? I had oem rotors for 30k/oem pads, and started getting shakes in the steering wheel. Now have autozone blanks with about 5k miles w/stoptech pads, and same thing, steering wheels vibrates/shakes when I brake. I'm not looking for slotted/drilled, just looking for good blank rotor.

THat is likely due to pad material unevenly distributed on the rotors. You can remove that material with some fine sand paper or brillo pad and quit replacing rotors so often.

Or you can do what I used to do. Take the car up to 60-70mph and brake hard down to 20mph 3-4 times in a row to remove it. THen drive around without braking or braking hard to let them cool down and don't hold the brakes on when stopped unless your car is going to roll.

I just deleted 17 useless, immature posts from this thread. If people wanna argue and act a fool and can't be civil about it, I'll be more than happy to remove that individual's right to post for a little while.

I just deleted 17 useless, immature posts from this thread. If people wanna argue and act a fool and can't be civil about it, I'll be more than happy to remove that individual's right to post for a little while.

In my earlier post (#116), I wanted to share not just an opinion, but my personal experience, as even a limited amount of track driving, with significant cool down between runs, still overwhelmed my brakes, even with HPS pads. This created a potentially dangerous situation.

I felt compelled to post in this thread because I did not want people to get too secure in their stock brake system by taking the OP's (and others) comments out of context, and find themselves in a spot of bother on the track, or on a "spirited" drive somewhere, as the stockers are not but so good. Even better fluid alone is not a bad idea.

While some MAY never need any brake upgrade, our (proud to be a new complete convert to the Subaru platform) cars are so good that it is kind of sad to think that there are those who won't drive this car to its potential - and if you do drive the car to its potential, you are going to have issues with the stock brakes.

On the Subaru, to say the stock brakes are plenty sufficient for some sort of "vast majority" of owners, is in my opinion an overstatement, or at least a statement that might lead to the "wrong" kind of owner/driver having a misplaced level of comfort in the stockers.

I just deleted 17 useless, immature posts from this thread. If people wanna argue and act a fool and can't be civil about it, I'll be more than happy to remove that individual's right to post for a little while.

Don't make me turn this bus around

Turn it around!!! I wanna go back home

Nah but seriously amusing to say the least, now as far as my opinion on the OP goes I concur they are not that much of a DIRE necessity... but then again it's YOUR money use it when YOU need it, call J.G. Went... mmmm yeah